Файл: 92FWD_24.pdf

Fig. 6 In-car Temperature Sensor/Aspirator

Assembly

WATER TEMPERATURE SENSOR

The water temperature sensor is located on the heater core mounting plate (Fig. 7). This is a thermistor which will pick up on the engines coolant temperature. The computer control uses this information to control the cold engine lockout time. The water temperature sensor is not serviceable and must be replaced if found to be defective.

Fig. 7 Water Temperature Sensor

SUN SENSOR

The sun sensor (Fig. 8) is mounted on the driver side of the vehicle on top of the instrument panel. This is not a thermistor type sensor but rather a photo diode. For this reason the sun sensor responds to sun light intensity rather than temperature. It is used to aid in determining proper mode door position.

The sun sensor is not serviceable and must be replaced if found to be defective.

Fig. 8 Sun Sensor

NONÐCOMPUTER AIDED DIAGNOSTIC TESTS

Determine whether the operator complaint is due to a system failure or improper operation of the ATC system. The system will to go into a maximum heat or cooling mode if the operator changes the temperature setting four or more degrees.

Check the following:

²Coolant level

²Refrigerant charge

²Drive belt tension

²Radiator air flow

²Radiator fan operation

²Air suction of In-car Temperature Sensor/Aspirator To check air suction of the Aspirator, place a small

piece of tissue paper over the Aspirator opening on the instrument panel. This opening is located to the right of the steering column. The tissue paper should cling to the opening if system is functioning properly.

Bring the engine to normal operating temperature and proceed with Computer Aided Diagnostic Procedures. Always test the entire system after each repair has been performed.

COMPUTER AIDED DIAGNOSTIC TESTS

The ATC control has a computer capable of troubleshooting the entire ATC system in approximately 60 seconds. The engine must be running and at normal operating temperature during the test to provide hot coolant for the heater.

During the ATC Diagnostic Test, the computer will calibrate the Mode and Blend Door actuators.

CAUTION: Do not remove the actuators from the heater-A/C unit assembly with power applied. Removal should only be done with the Ignition OFF. The actuators have no mechanical stops to limit the travel. If the actuator rotates and is not connected to the unit assembly, it will become un-calibrated.

The Diagnostic Test is capable of checking all electrical signals between the ATC Control Module, actuators, sensors and blower control.

The Diagnostic Test will display two types of FAILURE CODES (Fig. 9). The Failure Codes numbered 01 through 22, have been detected during the Diagnostic Test. Failure Codes numbered 23 through 28, have been detected during normal ATC operation. Failure Codes 23 through 28 would then be stored in the ATC control computer and are only being retrieved during the Diagnostic Test.

Fig. 9 Automatic Temperature Control Failure Codes

For electrical pin numbers, refer to the wiring Pin out charts on the following pages in this section.

(1)Start vehicle and allow engine to warm up.

(2)For two seconds, depress the DEFROST, FLOOR and AUTO buttons at the same time. The ATC control should begin to flash on and off.

(3)During the Diagnostic Test perform the following symptom tests:

(a)Do all display symbols and indicators illuminate ?

(b)Does the blower motor operate at its highest speed ?

(c)Feel the outlet temperature. Does it get hot and then cycle cold ?

(d)Does the air flow switch from DEFROST outlets and then cycle to PANEL outlets?

If you can answer NO to any of these questions,

proceed to step 4, otherwise proceed to step 5.

(4) If you answered NO to:

SYMPTOM A

The display symbols and indicators do not illuminate. Failure Codes are not displayed.

TEST

After self-diagnostic test is complete, select a mode that will display the malfunction.

ACTION

If the ATC system operates properly, and the display does not, replace ATC control panel computer.

SYMPTOM B

The blower motor does not operate.

CAUTION: Stay clear of blower motor and power module (PM) heat sink. Do not run system for more than 10 minutes with PM removed from A/C unit.

TEST

²Check all power module and blower motor connections. Use a voltmeter to test for 12 volts (ignition) at both ends of the fuse with ignition ON. If fuse is good, test the green wire at the blower motor connector for 12 volts (ignition) to body ground.

²Turn ignition to the ON position.

²With the blower motor still connected, check for 12 volts to body ground on the black/tan wire of the blower motor two way connector.

²Check for 12 volts at the Power Module pin #4 (BK/TN).

²Check for continuity from the Power Module pin #3 (BK) to chassis ground.

²Replace the Power Module.

ACTION

²If 12 volts is not detected, repair feed circuit. Refer to the Front Wheel Drive Car-Wiring Diagrams Service Manual.

²If 12 volts is not detected, repair wires of the blower motor or replace the blower motor.

²If 12 volts is not present, repair wire from the blower motor connector to the Power Module.

²If circuit is open, repair ground circuit of the Power Module.

²Replace the Power Module (power transistor open).

SYMPTOM C

The outlet air temperature does not become hot and then cycle to cold during self-test operation. Failure Codes are not displayed.

TEST/ACTION

²Make sure the blend-air door is properly attached to the actuator.

²If cold air is not discharged from the outlets, check the base A/C refrigerant system.

²Make sure heating operation works correctly, (water level, thermostat, heater hoses, heater core, etc.).

SYMPTOM D

Air does not flow from DEFROST outlets and then cycle to PANEL outlets during self-test operation.

TEST/ACTION

²Check linkages from the mode door actuator for binding.

²Check for proper door travel in the unit.

(5)The computer will do one of two things:

²Will return to the control settings that were selected before the Diagnostic Test was started. This means the test is over. If Failure Codes did not occur, and answers to questions (a), (b), (c), and (d) were YES, the entire system is operating correctly.

²The blower motor will stop and the computer will flash a FAILURE CODE number from 01 through 28. Record the number and then depress the PANEL button to advance to the next test. If the ATC control flashes one or more codes 23 to 28, the digits on the display will flash alternating Zeros. If you do nothing, these codes will remain stored within the ATC control computer. After all repairs have been made erase fault codes. Refer to Erasing Failure Codes 23 through 28 from ATC Control in this section.

Repair all Failure Codes in the order that they have been indicated, and then retest the system. If any blend door test fails, all remaining blend door tests will be skipped. IF any mode door tests fail, all remaining mode door tests will be skipped.

Diagnostic Test can be stopped at any time by depressing any button other than PANEL.

FAILURE CODE DEFINITIONS

Non-computer aided diagnostics should be performed first. Hood of vehicle should be closed during the diagnostic test to keep engine heat from effecting the ambient temperature sensor.

Also refer to the wiring Pin out charts (Figs. 10, 11, 12, 13, 14, or 15).

FAILURE CODE 1

²Involves the wiring or the ATC control head. FAILURE CODES 2, 13, 14, 15, 20, and 23

²Involves the wiring, blend-air door actuator, or the ATC control head.

FAILURE CODES 3, 16, 17, 18, 19, and 24

²Involves the wiring, mode door actuator, or the ATC control head.

FAILURE CODE 4

²Involves the wiring, blend-air door actuator, mode door actuator, fresh/recirc. door actuator, or the ATC control head.

FAILURE CODE 5

²Involves the wiring, fresh/recirc. door actuator, or the ATC control head.

FAILURE CODE 6

²Involves the compressor circuit signal wiring, or the ATC control head.

FAILURE CODE 7

²Involves the blower wiring, power module, or the ATC control head.

FAILURE CODES 8, 21, 22

²Requires replacing the ATC control head. FAILURE CODES 9, and 27

²Involves the wiring, sun sensor, or the ATC control head.

FAILURE CODES 10, and 28

²Involves the wiring, water temperature sensor, or the ATC control head.

FAILURE CODES 11, and 25

²Involves the wiring, ambient temperature sensor, or the ATC control head.

FAILURE CODES 12, and 26

²Involves the wiring, in-car temperature sensor/aspirator, or the ATC control head.

FAILURE CODE SERVICE PROCEDURES

The control keyboard will not function if pins 7, 9, 17, 19, or 20 of the 21-way wiring connector are shorted to battery voltage.

For electrical pin numbers, refer to the wiring Pin out charts (Figs. 10, 11, 12, 13, 14, or 15).

FAILURE CODE 1ÐOUTPUT FAILURE WITH ALL OUTPUTS LOW

(1)Remove pin #2 from 21-way connector on control and retest system. If code 01 does not appear, the control is good.

Disconnect 21-way connector from control. With an ohmmeter, measure the resistance between pin #2 and pin #12 of 21-way. This should be between 2,600 and 2,800 ohms. If yes, the power module is good.

Source of voltage on pin #2 is in the wiring. Repair and retest system.

(2)Remove pin #13 from 21-way connector on control and retest system. If code 01 does not appear, the control is good. Locate source of voltage on pin #13. Repair and retest system.

(3)Remove pin #5 from 21-way connector on control and retest system. If code 01 does not appear, the control is good. Locate source of voltage on pin #5. Repair and retest system.

(4)Remove pin #6 from 21-way connector on control and retest system. If code 01 does not appear, the control is good. Locate source of voltage on pin #6. Repair and retest system.

(5)Remove pin #15 from 21-way connector on control and retest system. If code 01 does not appear, the control is good. Locate source of voltage on pin #15. Repair and retest system.

FAILURE CODE 2ÐBLEND ACTUATOR DRIVE SIGNAL NOT HIGH

If both Failure Codes 2 and 3 occur simultaneously, do both procedures. There is typically only 1 failure.

(1) Disconnect terminal #6 on the ATC control 21way connector and retest the system. Note that removing this terminal may generate additional Failure Codes. Disregard these at this time.

(2)If Failure Code 2 reappears, replace control.

(3)If code 2 does not reappear, the problem is a shorted blend door actuator motor or a short to ground in circuit 33 (pin #6).

(4) Remove 21-way connector and check for continuity from pin #6 to chassis ground. There should not be any continuity. If continuity is there, repair wiring and retest.

(5) Check resistance across pins #6 and #4 of the 21-way for a shorted actuator motor. Resistance should be between 20 and 50 ohms. If not correct, replace actuator.

FAILURE CODE 4ÐACTUATOR DRIVE COMMON SIGNAL NOT HIGH

If both Failure Codes 4 and 5 occur simultaneously, do both procedures. There is typically only 1 failure.

FAILURE CODE 3ÐMODE ACTUATOR DRIVE SIGNAL NOT HIGH

If both failure codes 2 and 3 occur simultaneously, do both procedures. There is typically only 1 failure.

(1)Disconnect terminal #5 on the ATC control 21way connector and retest the system. Removing this terminal may generate additional Failure Codes. Disregard these at this time.

(2)If Failure Code 3 reappears, replace control.

(3)If code 3 does not reappear, the problem is a shorted mode door actuator motor, or a short to ground in circuit #35 (pin #5).

(4)Remove 21-way and check for continuity from pin #5 to chassis ground. There should not be any continuity. If continuity is there, repair wiring and retest.

(5)Check resistance across pins #4 and #5 of the 21-way connector for a shorted actuator motor. Resistance should be between 20 and 50 ohms. If not correct, replace actuator.

(1)Disconnect terminal #4 on the ATC control 21way connector and retest the system. Removing this terminal may generate additional Failure Codes. Disregard these at this time.

(2)If Failure Code 4 reappears, replace control.

(3)If code 4 does not reappear, the problem is a shorted actuator motor or a short to ground in circuit #34 (pin #4).

(4)Remove 21-way connector and check for continuity from pin #4 to chassis ground. There should not be any continuity. If continuity is there, repair wiring and retest.

(5)Check resistance across pins #4 and #5, #4 and #6, and #4 and #15 of the 21-way connector for a shorted actuator motor. Resistance should be between 20 and 50 ohms. If not correct, replace actuator involved.

FAILURE CODE 5ÐFRESH/RECIRC ACTUATOR DRIVE SIGNAL NOT HIGH

If both Failure Codes 4 and 5 occur simultaneously, do both procedures. There is typically only 1 failure.

24 - 68 HEATING AND AIR CONDITIONING

(1)Disconnect terminal #15 on the ATC control 21-way connector and retest the system. Removing this terminal may generate additional Failure Codes. Disregard these at this time.

(2)If Failure Code 5 reappears, replace control.

(3)If code 5 does not reappear, the problem is a shorted fresh/recirc door actuator motor. It could also be a short to ground in circuit #32 (pin #15).

(4)Remove 21-way connector and check for continuity from pin #15 to chassis ground. There should not be any continuity. If continuity is there, repair wiring and retest.

(5)Check resistance across pins #15 and #4 of the 21-way connector for a shorted actuator motor. Resistance should be between 20 and 50 ohms. If not correct, replace actuator.

FAILURE CODE 6ÐCOMPRESSOR DRIVE SIGNAL NOT HIGH

(1)Disconnect the low pressure cut out switch and retest diagnostics.

(2)If code 6 does not reappear, then the problem is in the A/C signal circuit C02. Check for wiring problem between the low pressure cut out switch and the engine controller, or a bad engine controller.

(3)If code 6 does reappear, remove the 21-way connector from the control and check for a short between pin #13 and chassis ground. This test will check the wire from the control to the low pressure cut out switch for a short to ground.

(4)If pin #13 shows continuity, repair circuit C02 and retest.

(5)If no continuity is shown, replace the ATC control and retest.

FAILURE CODE 7ÐBLOWER DRIVE SIGNAL NOT HIGH

First check the 4-way connector to the power module for correct installation

(1)With the ignition ON, check for ignition voltage to the power module pin #1 from the ATC control. If ignition is present at the power module, proceed to step 3. If not proceed to step 2.

(2)With the 21-way connector still connected and the ignition ON, check for power module ignition feed at the control pin #12. If ignition is not present, replace the control. If ignition voltage is present, repair the open in the wire between the control pin #12 and power module pin #1. Retest system.

(3)Turn ignition OFF and disconnect the 21-way connector. Measure the resistance between pins #2 and #12. The resistance should read between 2,600 and 2,800 ohms. If correct, replace the ATC control. If not correct, proceed to step 4.

(4)Remove the 4-way connector from the power module. Check for continuity between the ATC control pin #2 and power module pin #2. If no continu-

Ä

ity is shown, repair the wire for an open. If continuity is shown, replace the power module and retest.

FAILURE CODE 8ÐA/D CONVERTOR INTERNAL FAILURE

Diagnostics will indicate a Failure Code 8 if the internal reference voltage of the A/D Convertor is not correct. This Failure Code is not serviceable. If a Failure Code 8 occurs, the computer control head must be replaced.

FAILURE CODE 9ÐSUN LOAD SENSOR FAILURE

(1)Unplug the 21-way connector from the control and check pin #19 for continuity to chassis ground. If continuity is present, repair the wire shorted to ground. If no continuity is present, proceed to step 2.

(2)Plug the 21-way connector back in. Remove pin #19 from the 21 way connector and run diagnostics again. If Failure Code 9 is still present, replace the control. If code 9 is not present, replace the sun sensor.

FAILURE CODE 10ÐWATER TEMPERATURE SENSOR FAILURE

(1) Disconnect 21-way connector at control. Measure resistance between pin #17 and pin #7. This value will change with temperature. Refer to Temperature ReferenceÐFailure Code 10 chart.

TEMPERATURE REFERENCEÐFAILURE

CODE 10

(2) Check for continuity between pin #17 and chassis ground. If continuity is present, repair and retest.